A Study of High-Frequency Q (super -1) Lg in the Crust of South Korea

Knowledge of the value of Qlg^-1 is very important not only for scientific research but also for practical field research. We first measured the Qlg^-1 of South Korea by applying the coda normalization method to long-period recorded seismograms at four stations deployed by the Korea Institute of Geoscience and Mineral Resources. We analyzed 345 seismograms of 50 earthquakes that occurred between January 1999 to May 2002. The hypocentral distances range between 155 and 400 km. The regression of the plots of Qlg^-1 shows frequency dependence, which decreases from (1.4 (plus-minus) 1.0) x 10^–3 at 1.5 Hz to (0.3 (plus-minus) 0.1) x 10^–3 at 24 Hz. If we fit a power law depending on frequency, the best-fit line for Qlg^-1 is 0.0018f^–0.54. This value generally agrees with those of seismically inactive regions.